The goal of this interagency agreement is to provide support of National Toxicology Program (NTP) hazard identification (or hazard assessment) activities targeted toward the prevention of diseases or adverse effects caused by environmental exposure to chemical or physical agents. These studies capitalize on NIOSH's unique access to occupationally-exposed populations, and utilize NIOSH's expertise to complement NTP and NIEHS' capabilities. Under this agreement NIOSH will provide a real world context for NIEHS/NTP toxicology studies. To achieve this, NIOSH will characterize occupational exposure using a multidisciplinary approach to include toxicology, epidemiology, engineering, industrial science, and occupational medicine. The purpose of this project is to continue to identify workplaces engaged in the synthesis, manufacture and use of engineered nanomaterials, and to characterize the potential for worker exposure to selected engineered nanoparticles. The nanoparticles under study are commercially and scientifically exploitable and may pose a risk for adverse health effects, particularly respiratory disease. This study continues to have two focus areas: 1. Collect data on worker exposures to engineered nanomaterials that are established in the market; and 2. Collect preliminary data on materials that show good potential for high-volume commercialization. Both elements of this project are focused on addressing the lack of human exposure data. Having a better understanding of actual human exposures will aid NTP in prioritizing candidate materials for study. The data collected by this project will also assist NTP in focusing on the more appropriate form of a nanomaterial for those that have multiple categories, such as Carbon Nanotubes. NIOSH has developed and refined a standardized protocol for exposure assessment data collection that is flexible and allows for additional measurements to be taken as needed to adapt to different exposure scenarios as the applications and volumes of nanomaterials produced and used changes.